In order to password protect your Tumblr blog on mobile, you will first need to create a password. This password can be used to log into your Tumblr account on mobile devices. After you have created your password, you will need to enter it into the “Password” field when you sign in to your Tumblr account on mobile devices. Finally, you will need to enable password protection for your blog.
To do this, click on the “Settings” button on the blog’s front-page and then select the “Security” tab. On this tab, you will need to check the “Enable Password Protection” box and then enter your new password into the “Password” field. If you want, you can also enable two-factor authentication for your blog by clicking on the “Settings” button and then selecting the “Two-Factor Authentication” tab.